Electron discharge device



t. 25, 9 L. c. WERNER E'I'AL 0 2,385,435

ELECTRON DISCHARGE DEVICE Filed 001;. 23, 1944] Y AITORNEY PatentedSept. 25, 1945 Leo 0. Werner, Bloomfield, and Willard AL Laning'. GlenRidge, N.J., assignorsto" Westinghouse "Electric CorporatiomgEastPittsburgh, Pa., a

corporation of Pennsylvania Application October 23, 1944, Serial No.559,948

Claims. (01. 250- 275) Thisinvention relates to electron discharge. de-

vices'and more particularly to suohdevices employing filamentarycathodes.

' The particular device of the present invention is a triode vacuum tubeto be used in connection with such service as dielectric heating.equipment, and requiring high power output. A fundamental requirement,attainment of which is an object of the invention, is to provide a tubeof reasonable size and yet with a cathode of sturdy construction,capable of producing high power output.

" A'further object of the invention is to adapt the structure toutilization of smaller conductors than heretofore required for tubeshaving corresponding power output.

Another object of the invention is toobtain extensive emission area buta relatively short over-all length of tube.

"Again, an object of the invention is to utilize readily made stampingsfor filament or cathode connections.

Another object of the invention isv to provide tensioning means for thefilament strands of improved character and without material in.. creaseof length of the device.

Yet another object is to simplify the dielectric spacing of thefilam'entconnections.

'Still'further objects of the invention will appear to those skilled inthe art to which it appertains'as the description proceeds, both bydirect recitation thereof and by implication from the context.

Referring to the accompanying drawing in whichlike numerals of referenceindicate similar parts throughout the several views V Figure 1 issubstantially an elevation of an electron discharge device, the bowl andanode ofwhich are broken away and the grid shown in longitudinalsection;

Figure '2 is sectional view on line IIII of Fig. 1

Figure 3' is a sectional view on line'III-III of i Figure 4 is asectional view similar to Fig. 2 but showing a neutral connector for usewith M- type filament strands; and

Figure 5 is a sectional view on line V-V of Fig. 4.

In the specific embodiment of the invention illu'strated in saiddrawing, a part of an electron discharge device, generally identified asa transmitting or power tube, is depicted exemplifying the invention. Itshould be understood, however, that theinvention is applicableto otherelectromc devices than'the, particular transmitting or power tube hereselectedfor illustrative purposes.

'The specific tube shown comprises a glass or other ceramic bowl orcasing portion 10 here represented as part of an evacuated envelope,

' unified with appropriate posts, of which one post l2 leads'to andupwardly upon the axis of the device and other posts l3 are spacedtherearound Within the basejportion'of the. envelope. At the upper rimof 'the' b'owl l0, there is sealed thereto a metallic cylindricaldome-like anode M, which, with said bowl constitutes a closed. andevacuated envelope.

Coaxially within the said anode andspaced in parallelismtothe'cylindrical'wall thereof is a grid IS, the upper end of'which hasa trans- Verse supporting plate l5 as part thereof and the lower end ofwhich hasa metallic flanged collar 11 integral therewith. One or more ofsaid posts [3 are attached to the flange of said collar IT for rigidlymounting the said grid.

The filament or cathode, designated generally in Figures 1 to 3 byreference numeral [8, comprises a plurality of strands, the majorportions of which are parallel and together constitute a cylindricalassembly coaxial to the .grid and anode. In the showing of Figures 1 to3 the cathode is composed of a plurality of, hairs-pin sections eachhaving two parallel legs or strands IS with the endstoward the bowl endof the device and the two strands. offeach section in electrical series.The several se'ctionsare" in electrical. parallel.

In the showing of Figures'4 and 5, the cathode 18a is composed of aplurality of M-type sections each having four parallellegs or strands19a in electrical series and the several sections inelectrical'parallel. Both constru'ctionsprovide bi'ghts 2|] at the upper or remotepart of the strands from the section ends, said bights havingappropriate support .by which the strands are both held and tensioned.In the construction with the'hairpin' filament'sections, the bights arecarried by a metallic plate 2!, the mid-portion whereof rests upon aninsulating button 22 slidable upon the aforementioned axial post 12.With the M-typ'e filament sections-of.- Figs. 4 and 5, the plate it isinsulativeor the two: upper bights of the M-filament are otherwisemaintained electrically from, shorting acrossthe plate.

In any event, upward pressure upon the button 22 transmits through theplate to the filament bights and exerts tension on the several strandsof the filament to keep them taut.

Upward pressure is applied to said button by a coaxial sleeve 23slidably mounted on the axial post I2.- Preferably -the inside diameterof said sleeve exceeds the outside diameter or said post so as to be outof contact and to avoid introduction of frictional resistance tomovement of the sleeve. Caps 24 are fitted over the ends of said sleeve,said caps having holes which substantially fit the post and since thecaps are preferably sheet metal, the edges of the holes are of limitedarea and thus have minimum contact with the post and interfere to noappreciable degree with free sliding on the post, but maintain thesleeve substantially coaxial to the post. The upper cap 24 provides afiat bearing surface against button 22 distributing pressure of the endedge of the sleeve over a more extensive area of the button than wouldoccur with direct engagement of the sleeve against the button.

The lower cap 24 is interposed between the lower edge of sleeve 23 andthe upper end of a coil spring 25 mounted on said post I2. Said springis under compression, its lower end engaging a shoulder 26 of a fixedcollar 21 carried by the post. As shown, said fixed collar has, belowthe shoulder, a lower end portion which is of equal internal diameter tothe exterior diameter of the post and welded, soldered orotherwisepermanently afiixed to the post. Above the said shoulder, said fixedcollar has an upper portion having a larger internal diameter than theexternal diameter of the cap and spring so as not to interfere with freeoperation of either and receives the spring therein. Said upper portionextends well above the cap and has an outwardly directed flange 28 atits upper end.

An inverted metallic cup 29 coaxial with said sleeve is welded, solderedor otherwise secured to said flange. Preferably said sleeve projectsthrough the transverse wall of said cup so that the said wall of the cupis at the under side of the flange. The peripheral side wall of the cupdepends from said transverse wall, is cylindrical in character and at adistance from the sleeve, thereby providing an insulator-receivingdownwardly open pocket or hollow. The lower edge of the cylindrical sidewall of said cup is provided with a plurality of ears 30 in a sequentialcircular series aroundthe cup. From each ear to the next in sequence isleft a considerable space for purposes hereinafter related. The earshave their basal portions in continuation of the cylindrical wallparallel to the axis and have an intermediateportion which bendsradially outward and an end portion which is bent to again continueparallel to the 'axis but further therefrom radially than the basalportion. The radially extending intermediate portions of the earsaccordingly define a transverse plane which is ofiset in an axialdirection from the plane defined by the lower edge appearing between theears of the peripheral wall of the cup. Description thus far given ofthe inverted cup and its ears is equally applicable to all figures ofthe drawing. However, in Figures 1 to 3 the recurrence of ears in thesequence is more frequent than in Figures 4 and 5. I

Below the inverted cup, entirely out of contact therewith, is a lowercup 3|, the hollow of which is directed upwardly or toward the hollow ofthe upper or inverted cup. This lower cup has a hole or opening 32centrally of its transverse or bottom wall, which is larger than theoutside diameter of aforementioned fixed collar 21. The hollows of thetwo cups 29 and 3| are of substantially the same size and shape andreceive an annular insulator or other ceramic 33, the ends ofwhich arein engagement with the transverse walls of the cups and the length ofwhich is proportioned to the depth of the two cups so that ears 34 ofthe lower cup which extend first upwardly and then outwardly have thesaid outwardly directed portions thereof in the same plane as theoutwardly directed portions of the aforementioned ears of the upper cup29. The said ears of the lower cup project from an edge of the lowercup, which is below or offset in a direction axially of the device fromthe said plane of the outwardly projecting portion of said ears so as tomake no contact with the upper cup or its ears. The ears of the lowercup are, like the ears of the upper cup, in a sequential annularseries'around the cup, and the ears of one cup alternate between ears ofthe other, andsuccessive ears are spaced from 'each other in a directionperipherally of the cups.

In the showing of Figures 4 and 5, the ears of the upper and lower cupsare grouped as pairs, and between pairs a considerable gap is providedand in these gaps are radially projecting portions of ears 35 on awasher-like neutral plate 36, these ears being shown as double the widthof the cup ears and forming therewith a continuous sequential series ofears having portions projecting radially from the insulator or ceramic.Figures 4 and 5 show the insulator as divided longitudinally on theplane of the projecting portions of the ears and washer-like neutralplate 35 into two sections 3%, so that said plate is mechanicallymounted from but is electrically separated from the said cups. The outerends of all ears are directed downwardly and together define acylindrical surface interrupted peripherally by the recurring gapsbetween successive ears. The foot portions or ends of the filament orcathode sections depend next the downwardly directed end portions of theears, one end of each cathode section being secured, as by welding, toan ear from one cup and the other end being secured to an ear of theother cup. In Figures 4 and 5 utilizing an M-type filament, theintermediate legs or strands are both secured to the depending portionof a double wide ear of the neutral plate 35.

It is now appropriate to observe that upward displacement of the cupsand insulator assembly in both structural showings of the drawing, isprevented by overlying flange 28 of fixed collar 27, and that downwarddisplacement is prevented by the tension of the filament strandsattached to the ears of the lower cup. As fixed collar 21 is rigid withrespect to post [2, and as ceramic 33 substantially fits upon thatcollar and within the cups, lateral displacement is prevented.

In order to be assured of no angular or rotational displacement, dowelpins 31 may be secured to the transverse walls of the cups directedinwardly of the cups and into appropriate holes in the ceramic. With theinterpositioning of plate 36 between ceramic sections as shown in Figure5, another dowel. 38 may be provided through said plate and projectingat both ends into the ceramicsections.

The filament current is supplied through centralpost [2 to the fixedcollar 21, and thence to the upper cup and one foot portion of the filament. Another lead-in connection 39 is soldered or welded to the bottomtransverse wall of the lower cup 3|, the ears of which carry the otherfoot portion of the filament sections. Thus, while the filament may betensioned by spring pressure, the necessary movement for such tensioningis at the bight portions of the filament sections and requires nomovement at the lead-in or foot ends thereof, consequently enablingrigid and inflexible connections to be employed. The structure shown hasa further advantage in that the ceramic or annular insulator 33 isphysically interposed between the direct line of radiation of heat fromthe filament to the spring 25, and the ceramic accordingly functionsboth as an electrical and a heat insulator.

We claim:

1. An electron discharge device comprising a cathode assembly having afilament with a plurality of strands, said filament providing footportions and a bight portion, a rod support, means slidable on said rodsupport and carrying said bight portion, a fixed collar on said rodsupport at the foot portions of the filament, said collar counteractingtension from said foot portions of the filament, and tension applyingmeans interposed between said collar and bight portion.

2. An electron discharge device comprising a cathode assembly having afilament with a plurality of strands, said filament providing footportions and a bight portion, a rod support, means slidable on said rodsupport and carrying said bight portion, a fixed collar on said rodsupport at the foot portions of the filament, said collar counteractingtension from said foot portions of the filament, a spring carried bysaid collar, and a sleeve around said rod support interposed betweensaid spring and slidable means for applying tension to the bight portionof the filament from the said spring.

3. An electron discharge device comprising a fixed cylindrical andflanged member, a pair of hollow cups on said member, said cups havingthe hollows thereof directed toward each other, an annular insulator insaid cups and around a part of said member, said cups having earsportions whereof project in a common plane radially outward from saidannular insulator, and filament strands secured to said ears.

4. An electron discharge device comprising a fixed cylindrical andflanged member, a pair of hollow cups on said member, said cups havingthe hollows thereof directed toward each other and their edges separatedfrom each other, an annular insulator in said cups maintaining said cups1 aligned coaxially and said edges separated, said cups each having anannular sequential series of ears, the ears of one cup being situatedbetween ears of the other out of contact therewith, and filament strandssecured to said ears.

5. An electron discharge device comprising a fixed cylindrical andflanged member, a pair of hollow cups on said member, said cups havingthe hollows thereof directed toward each other and their edges separatedfrom each other, an

6. An electron discharge device comprising a filamentary cathode ofgenerally cylindrical form composed of a plurality of hairpin sectionseach having a pair of strands having foot ends, a

- means for mounting said foot ends and supplying electrical heatingcurrent thereto, comprising a pair of hollow cups coaxial with saidcathode, said cups having the hollows thereof directed toward eachother, an annular insulator in said cups maintaining said cups alignedcoaxially, said cups having an annular sequential series of evenlyspaced ears, the ears of one cup alternatin in the series with ears ofthe other cup and each of said ears being out of engagement with ears onboth sides thereof in the series, and one ear of one cup having one footend of one filament section secured thereto and an ear of the other cuphaving the other foot end of the filament section thereto, whereby saidfilament section is in electrical series from one cup to the other,

7. An electron discharge device comprising a filamentary cathode ofgenerally cylindrical form composed of a plurality of strands grouped toform successive M-type sections, each strand having a foot end, a meansfor mounting said foot ends and supplying electrical heating current inseries through the several strands forming an M section, comprisin apair of hollow cups and an interposed washer-like plate coaxial with thecathode, an annular insulator having one section disposed in one cup andengaging one face of said plate and having another section disposed inthe other cup and engaging the other face of said plate, said cups andplate having ears projecting radially in a common plane and in asequential series peripherally of said means, the foot ends of theextreme strands of a M section of the filamentary cathode beingconnected respectively to ears of the two cups, and the intermediatestrands of the M section both being connected to a single ear of thesaid plate.

8. Mounting means for foot ends of multistrand filaments comprisingopposed axially aligned cups having hollows directed toward each other,an insulator in said cups holding the same apart and axially aligned,and ears at the facing edges of said cups, said ears having radiallyprojecting portions, and the radially projecting portions of the ears ofboth said cups being in substantially a common plane.

9. Mounting means for foot ends of multistrand filaments comprisingopposed axially aligned cups having hollows directed toward each other,cars on both cups at the facing edges thereof and having radiallyprojecting portions, all of which are substantially in a common planeand of equal size, the ears of one cup alternating with ears of theother and equally spaced from each other.

10. Mounting means for foot ends of multistrand filaments comprisingopposed axially aligned cups having hollows directed toward each otherand having a plate interposed between said cups, insulator sections insaid cups and engaging said plate at opposite faces thereof, said platehaving ears with radially directed portions in the plane of the plate,and said cups having ears with radially directed portions in a planecommon to the plane of said plate.

LEO C. WERNER. WILLARD A. LANING.

